CAMBRIDGE, Mass. — The global economy is a runaway train that is slowing, but not quickly enough. That is what the extraordinary runup in prices for oil, metals and food is screaming at us.

The spectacular and historic global economic boom of the past six years is about to hit a wall. Unfortunately, no one, certainly not in Asia or the United States, seems willing to bite the bullet and help engineer the necessary coordinated retreat to sustained "subtrend growth," which is necessary so that new commodity supplies and alternatives can catch up.

Instead, governments are clawing to stretch out unsustainable booms, further pushing up commodity prices, and raising the risk of a once-in-a-lifetime economic and financial mess. All this need not end horribly, but policymakers in most regions have to start pressing hard on the brakes, not the accelerator.